JP2011033022A - Impeller cover and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an impeller cover for protecting an impeller from damage. <P>SOLUTION: The impeller cover 50 includes a removable body 50 having a first face 52 and a second face 54 opposing the first face, the second face 54 being configured to match a front face 14a of the impeller 14 of the compressor, and further having a frontal portion covering an entire frontal portion of the impeller 14 of the compressor, and a fixing mechanism connected to the removable body 50 and being configured to fix the impeller cover to the impeller 14 of the compressor. The impeller cover 50 is disposable. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  Embodiments of the presently disclosed subject matter generally relate to methods and systems for protecting devices from erosion and / or material deposition, particularly mechanisms and techniques.

  Over the past years, the presence of compressors has been more prominent in the oil and gas industry. The compressor is used not only for collecting oil and gas but also for transporting oil and gas from the collection point to the consumption place. Compressors are further used in a wide variety of petrochemical processing, such as the production of liquefied natural gas (LNG), ethylene, polyethylene and the like.

  For this reason, compressor construction and maintenance are becoming increasingly important in these industries. There are many types of compressors, such as centrifugal compressors, screw compressors, axial compressors, etc., but most compressors face similar problems. These problems include, but are not limited to, material deposition on various components of the compressor and / or erosion of some components of the compressor.

  One mechanism that causes compressor degradation is fouling. Fouling is caused by particles adhering to the airfoil and annulus surfaces of the compressor. Adhesion is caused by oil mist, water mist or other mist that may be present in the compressor. As a result, adhesion of a substance that causes an increase in surface roughness and changes the shape of the airfoil to some extent occurs. FIG. 1 is a diagram showing the deposition of such substances on the impeller of a centrifugal compressor. FIG. 2 is a diagram showing the adhesion of substances on the conical discharge part of the compressor. Although the airfoil will be described in particular, the same applies to the other components of the compressor. Since the contaminants are small, for example some contaminants are less than 2 μm, fouling is currently eliminated by washing.

  This means that the compressor is constantly inspected and the compressor operation is stopped when adhesion is detected. The adhering compressor components are then either removed from the compressor or washed with the components attached to the compressor if access to the contaminated compressor parts is possible. It is washed by All these operations require that the compressor process be stopped, i.e. the entire production cycle is affected by this cleaning process. This results in production downtime and production losses that are not desired by the compressor operator.

  Hot corrosion is another mechanism that degrades parts of the compressor. Hot corrosion is a material loss of the flow path component caused by a chemical reaction between the flow path component and certain contaminants such as salts, mineral acids or reactive gases. The products of these chemical reactions deposit as scale on the compressor components. On the other hand, high temperature oxidation is a chemical reaction between constituent metal atoms and oxygen in the surrounding hot gas environment. Oxide scale protection is also reduced by some mechanical damage such as cracks or delamination during thermal cycling.

  Another mechanism that can damage the compressor components is erosion by impact. Various particles are circulated through the compressor while colliding with the flow path surface of the compressor. In order to cause erosion by impact, these particles generally must be greater than 20 μm in diameter. Since modern filtration systems used in the industry generally remove most of the larger particles, erosion is likely to become even more problematic in aero engine applications. Erosion can also be a problem for compressors or pumps that are driven in situations where process gases or fluids carry solid materials. Damage is often caused by large foreign objects that impact the flow path components. These materials can enter the compressor along with the gas stream. Carbon deposits that delaminate from the fuel nozzle can also cause damage to the compressor components.

  All these processes, ie erosion, adhesion or damage to the airfoil, change the airfoil geometry. Degradation of the blades of these devices is accompanied by changes in exit angle and increased losses. When the blades are operating at or near transonic speed, the increase in deposits or roughness (and the accompanying increase in boundary layer thickness) also reduces the flow rate that can pass through the blade row. As the boundary layer thickness on the vanes and sidewalls increases, the flow capacity decreases, especially in the substantially choked state. On the other hand, when the trailing edge is eroded, the throat width of the blade increases and the flow rate increases, but the head drop amount decreases. There is no known effective way to prevent the above process other than cleaning contaminated components of the compressor.

  Accordingly, it would be desirable to provide a system and method that avoids the above problems and drawbacks.

  According to one exemplary embodiment, there is an impeller cover that covers at least one surface of the compressor impeller. The impeller cover has a first surface and a second surface opposite to the first surface, the second surface configured to match the front surface of the compressor impeller, A removable body further comprising a front portion covering the entire front portion of the compressor impeller, and an attachment mechanism connected to the removable body and configured to secure the impeller cover to the compressor impeller; including.

  According to another exemplary embodiment, a housing, an impeller provided on an axis inside the housing and configured to rotate about a longitudinal axis, and an impeller that covers at least one surface of the impeller There is a compressor including a cover. The impeller cover is first and second surfaces, wherein the second surface is opposed to the first surface, and the second surface is configured to match the front surface of the impeller. A removable body having two sides and further having a front portion covering the entire front portion of the compressor impeller. The impeller cover further includes an attachment mechanism connected to the removable body and configured to secure the impeller cover to the impeller. The first surface of the removable body is configured to have a profile that achieves a predetermined aerodynamic characteristic, and the profile of the second surface of the removable body that corresponds to the front surface of the impeller has a predetermined aerodynamic profile. The aerodynamic characteristics are less desirable than the characteristics, and the impeller cover is disposable.

  According to yet another exemplary embodiment, there is a method for protecting a compressor impeller from material adhesion and / or erosion. The method includes the steps of covering the front surface of the impeller with an impeller cover and securing the impeller cover to the impeller.

  The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one or more embodiments and, together with the detailed description, explain these embodiments.

1 is a schematic view of an impeller of a compressor with material deposit thereon. Fig. 4 is a schematic illustration of a conical discharge of a compressor with material deposit thereon. 1 is a schematic diagram of a compressor. Fig. 4 is a schematic view of the impeller of the compressor of Fig. 3. 1 is a schematic illustration of an impeller and an impeller cover according to an exemplary embodiment. 1 is a schematic illustration of an impeller cover according to an exemplary embodiment. 1 is a schematic illustration of an impeller cover according to an exemplary embodiment. 2 is a schematic illustration of the rear of an impeller cover according to an exemplary embodiment. 4 is a flow diagram illustrating steps of a method for protecting a compressor impeller, according to an exemplary embodiment.

  The following exemplary embodiments are described with reference to the accompanying drawings. The same reference numbers in different drawings identify the same or similar elements. The following detailed description does not limit the invention. Rather, the scope of the present invention is defined by the appended claims. In the following embodiments, the terminology and structure of the compressor will be described for simplicity. However, the embodiments described below are not limited to compressors and may be applied to other systems having components that are affected by material deposition and / or erosion.

  Throughout this specification the description “one embodiment” or “an embodiment” refers to at least one embodiment of the disclosed subject matter whose particular function, structure, or characteristic is described in the context of that embodiment. Means included. Thus, the phrases “in one embodiment” or “in an embodiment” appearing in various parts throughout this specification are not necessarily referring to the same embodiment. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner in one or more embodiments.

  According to an exemplary embodiment, the disposable impeller cover is formed to cover at least the front surface of the compressor impeller. Covering the front of the compressor impeller with the impeller cover prevents material sticking and / or erosion of the impeller. If material adheres on the impeller cover, the compressor may be stopped for a short time, the impeller cover removed, and a new impeller cover attached to the compressor impeller. Using the disposable impeller cover saves time and extends the life of the impeller.

  According to the exemplary embodiment shown in FIG. 3, the compressor 10 includes a casing 12 in which at least one impeller 14 is provided. The impeller 14 has an impeller hub 16 in which the impeller blades 18 are formed. The impeller 14 is attached to a shaft 20 that rotates about the longitudinal axis Z. The shaft 20 is supported by a bearing 22. The compressor has an inlet 24 and an outlet 26.

  The fluid supplied to the inlet 24 is accelerated by the impeller 14 and discharged at a higher pressure at the outlet 26. The impeller 14 has a front region that directly faces the flowing fluid and a rear region that is shielded from contact with the fluid by the front region. The front and rear regions are clearly shown in FIG. The front region 30 is illustrated with direct contact with the flowing fluid 34, and the rear region 32 of the impeller 14 is illustrated without interacting with the flowing fluid 34.

  As described above, the components of the fluid 34 adhere as the scale 36 on the impeller 14 as shown in FIG. According to the exemplary embodiment shown in FIG. 5, the impeller cover 50 is removably attached to the impeller 14 to prevent the scale 36 and / or other damage factors from directly affecting the impeller 14. . Therefore, the first surface 52 (front side surface) of the impeller cover is manufactured to closely resemble the front surface 14 a of the impeller 14. The contour of the first surface 52 of the impeller 50 should closely resemble the contour of the front surface 14a of the impeller 14 so that the aerodynamic characteristics of the impeller 14 are not degraded by the impeller cover 50. . Some characteristics of the impeller 14 that must be maintained by the impeller cover 50 are the impeller (compressor) efficiency, the compressor polytrope head, the range to the compressor stonewall (choke), and the compressor surge. Range. According to an exemplary embodiment, the impeller cover 50 maintains only the impeller efficiency.

  According to yet another exemplary embodiment, the front face 14a of the impeller 14 is machined to be different from the desired front face of a similar impeller, i.e. the front face 14a of the impeller 14 does not achieve the above characteristics. Designed to. That is, the impeller 14 has a (defective) front surface 14a with undesirable properties that would not be used by those skilled in the art in conventional compressors or turbines. However, the impeller cover 50 is designed in such a manner that the first surface 52 of the impeller cover 50 achieves the above characteristics when covering the defective front face 14a. Therefore, the impeller 14 alone does not have the desired characteristics of a good compressor, but the combination of the impeller 14 and the impeller cover 50 achieves the desired characteristics.

  According to yet another exemplary embodiment, the second surface 54 opposite the first surface 52 of the impeller cover 50 matches the front surface 14a of the impeller 14 so that the impeller cover 50 and the impeller 14 must be prevented from forming an air pocket between the two. The impeller cover 50 is formed of plastic, metal or other suitable material recognized by those skilled in the art. In one application, the impeller cover 50 has a first region made of a certain material and a second region made of a second material different from the first material. For example, FIG. 6 shows a front region 56 of the impeller cover 50 and a rear region 58 of the impeller cover 50. In this example, the front region 56 may be made of any plastic, and the rear region 58 is formed of a specific plastic. In one exemplary embodiment, the particular plastic is a stretchable plastic that stretches this portion around the rear region 32 of the impeller 14 to secure the impeller cover 50 to the impeller 14. In yet another exemplary embodiment, the particular plastic is a heat shrinkable plastic that shrinks under heat treatment. This is also used to attach the entire impeller cover 50 to the impeller 14. In yet another exemplary embodiment, the entire impeller cover 50 is formed from a specific plastic.

  According to yet another exemplary embodiment, as shown in FIG. 7, a portion of the body of the impeller cover 50 has a first thickness t1 60, and another portion of the body is a second thickness. It has a thickness t2 62. In one exemplary embodiment, the impeller cover 50 has a uniform thickness. Those skilled in the art will appreciate that the thickness of the impeller cover 50 depends at least on the size of the impeller and the shape of the impeller. However, the thickness of the impeller cover 50 must be such that the first surface of the impeller cover 50 closely resembles the front surface 14a of the impeller 14.

  The impeller cover 50 includes an attachment mechanism that fixes the impeller cover 50 to the impeller 14. One such mechanism is described above and is a stretchable material that is attached to the body of the impeller cover 50. The stretchable material forms a rear portion 58 of the impeller cover 50 and extends over the rear region 32 of the impeller 14. Another such mechanism is the heat shrinkable material described above that is used as the rear portion 58 of the impeller cover 50. In other exemplary embodiments, the entire impeller cover 50 is formed of a stretchable or heat-shrinkable material.

  According to yet another exemplary embodiment, the impeller cover 50, shown in rear view in FIG. 8, has a hole 80 or attachment device 84 that secures the impeller cover 50 to the impeller 14. In order to fix the impeller cover 50 to the impeller 14, the holes 80 are connected to each other by a strap 82, or the attachment device 84 is connected to the receiving part 86. The hole 80, the strap 82, the attachment device 84 and the receiving portion 86 are formed in the rear portion 58 of the impeller cover 50.

  According to yet another exemplary embodiment, a pocket 88 is formed on the second surface 54 of the impeller cover 50. The pockets 88 are formed discretely, i.e., at any location, or continuously, i.e., covering the second surface 54. The pocket 88 includes a material that adheres the impeller cover to the impeller, such as an adhesive-like material. Other materials that join the impeller cover and impeller are also used. According to this application, when the impeller cover 50 is attached to the impeller 14, the pocket 88 is fixed to the front surface 14 a of the impeller 14 and fixes the impeller cover 50 to the impeller 14. As will be appreciated by those skilled in the art, other mechanisms for securing the impeller cover to the impeller may be used without departing from the scope of these embodiments.

  In one exemplary embodiment, the impeller cover 50 covers only a portion of the impeller 14, ie, the front surface 14a. In yet another exemplary embodiment, the impeller cover 50 covers the impeller 14 entirely, i.e., both the front and rear surfaces of the impeller 14. Regardless of the ratio of the impeller 14 covered by the impeller cover 50, the impeller cover 50 is removable (disposable) and is replaced with a new impeller cover as necessary. In one exemplary embodiment, it is not necessary to disassemble the compressor in removing the old impeller cover and installing a new impeller cover.

  A method for protecting an impeller of a compressor using an impeller cover will now be described according to an exemplary embodiment. As shown in FIG. 9, the method includes a step 900 for covering the front surface of the impeller with the impeller cover and a step 902 for fixing the impeller cover to the impeller. The method further includes removing the impeller cover and installing a new impeller cover. The impeller cover is configured such that the front side surface of the impeller cover has a contour that achieves a predetermined aerodynamic characteristic, and the contour of the rear surface of the impeller cover corresponding to the front surface of the impeller is desirably as high as the predetermined aerodynamic characteristic. Molded to have no aerodynamic characteristics.

  The disclosed exemplary embodiments provide an impeller cover, a compressor system, and a method for protecting parts of the compressor from degradation. It should be understood that the description is not intended to limit the invention. Rather, the exemplary embodiments are intended to embrace alternatives, modifications and equivalents that fall within the spirit and scope of the invention as defined by the appended claims. Furthermore, in the detailed description of the exemplary embodiments, numerous specific details are set forth in order to provide a comprehensive understanding of the claimed invention. However, one of ordinary skill in the art appreciates that various embodiments can be practiced without such specific details.

  Although features and elements of exemplary embodiments of the invention have been described in specific combinations in the embodiments, each feature or element can be used alone or in the specification without using other features and elements of the embodiments. It can be used in various combinations with or without other features and elements disclosed in the document.

This written description uses examples to disclose the invention, including the best mode, and further includes any and all aspects of the manufacture and use of the device or system and the practice of the methods incorporated herein. It enables the trader to practice the present invention. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are included within the scope of the claims if they have structural elements that do not differ from the language of the claims or if they contain structural elements that are equivalent to the language of the claims. Intended.

Claims (15)

An impeller cover (50) covering at least one surface (14a) of the impeller (14) of the compressor (10),
A first surface (52) and a second surface (54) facing the first surface (52), the front surface (14a) of the impeller (14) of the compressor (10); A removable body (50) having a second surface (54) configured to mate, and further covering the entire front portion of the impeller (14) of the compressor (10) A removable body (50) having a portion (56);
An attachment mechanism (58, 80, 82, connected to the removable body (50) and configured to secure the impeller cover (50) to the impeller (14) of the compressor (10) 84, 86)
The impeller cover (50) is disposable, the impeller cover (50).   The removable body (50) of the impeller cover (50) has a rear portion (58) that partially covers the rear portion of the impeller (14), and the impeller cover (50) The impeller cover of claim 1, wherein the front portion (56) is configured to be in direct contact with a fluid flow through the compressor (10).   The rear portion (58) of the removable body (50) forms the attachment mechanism (58, 80, 82, 84, 86) and at least partially covers the rear portion of the impeller (14). The impeller cover according to claim 2, wherein the impeller cover is configured so as to be elastically extendable.   The rear portion (58) of the impeller cover (50) is connected by a strap (82) so that the impeller cover (50) is fixed on the impeller (14) of the compressor (10). The impeller cover according to claim 2, comprising a hole (80) configured to, the front portion (56) of the impeller cover (50) having no holes.   The first surface (52) of the removable body (50) is configured to have a profile that achieves predetermined aerodynamic characteristics and corresponds to the front surface (14a) of the impeller (14). An impeller cover according to any one of the preceding claims, wherein the contour of the second surface (54) of the removable body (50) has an aerodynamic characteristic that is less desirable than the predetermined aerodynamic characteristic. .   The vane according to any one of the preceding claims, wherein the attachment mechanism (58, 80, 82, 84, 86) comprises adhesive pockets (88) distributed over the second surface (54). Car cover.   The impeller cover according to claim 5, wherein the adhesive pocket (88) covers the entire second surface (54) of the impeller cover (50).   The impeller cover according to any one of claims 1 to 7, wherein the removable body (50) is formed of plastic or metal or a combination of plastic and metal.   9. The impeller cover according to claim 1, wherein the attachment mechanism (58, 80, 82, 84, 86) is made of a material different from that of the removable body (50).   The attachment mechanism (58) is heat sensitive, the attachment mechanism (58) is tightened by heat treatment applied to the attachment mechanism (58), and the impeller cover (50) is attached to the compressor (10). 10. An impeller cover according to any one of the preceding claims, configured to be fixed to the impeller (14). A housing (12);
An impeller (14) provided on the shaft (20) inside the housing (12) and configured to rotate about a longitudinal axis (Z);
An impeller cover (50) covering at least one surface (14a) of the impeller (14),
It has a first surface (52) and a second surface (54), the second surface (54) faces the first surface (52), and the second surface (54). Is a removable body (50) configured to match the front surface (14a) of the impeller (14), and further the entire front portion of the impeller (14) of the compressor (10) A removable body (50) having a front portion (56) covering
An attachment mechanism (58, 80, 82, 84, 86) connected to the removable body (50) and configured to secure the impeller cover (50) to the impeller (14). An impeller cover (50),
The first surface (52) of the removable body (50) is configured to have a profile that achieves predetermined aerodynamic characteristics and corresponds to the front surface (14a) of the impeller (14). The contour of the second surface (54) of the removable body (50) has an aerodynamic characteristic that is less desirable than the predetermined aerodynamic characteristic;
The impeller cover (50) is a disposable compressor (10).   The removable body (50) of the impeller cover (50) has a rear portion (58) that partially covers the rear portion of the impeller (14), and the impeller cover (50) The compressor according to claim 11, wherein the front portion (56) of the is in direct contact with a fluid flow through the compressor (10).   The rear portion (58) of the removable body (50) forms the attachment mechanism (58, 80, 82, 84, 86) and at least partially covers the rear portion of the impeller (14). The compressor according to claim 12, wherein the compressor is configured to be elastically covered. A method for protecting an impeller (14) of a compressor (10) from material adhesion and / or erosion, comprising:
An impeller cover (50) is used to cover the front surface (14a) of the impeller (14) so that the front side surface (52) of the impeller cover (50) has a contour that achieves predetermined aerodynamic characteristics. The contour of the rear surface (54) of the impeller cover (50) that is configured and corresponds to the front surface (14a) of the impeller (14) has an aerodynamic characteristic that is less desirable than the predetermined aerodynamic characteristic. Steps,
Fixing the impeller cover (50) to the impeller (14). Removing the impeller cover (50);
Covering the front surface (14a) of the impeller (14) with a new impeller cover (50).

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